||is aperture elliptical?|
|EXPONENT||long||2||exponent for boundary equation in elliptical mode. 2 is a true ellipse.|
||y exponent for boundary equation in elliptical mode. If zero, defaults to EXPONENT.|
|OPEN_SIDE||STRING||NULL||which side, if any, is open (+x, -x, +y, -y)|
|GROUP||string||NULL||Optionally used to assign an element to a group, with a user-defined name. Group names will appear in the parameter output file in the column ElementGroup|
This element sets the aperture for itself and all subsequent elements. The settings are in force until another MAXAMP element is seen.
This can introduce unexpected behavior when beamlines are reflected. For example, consider the beamline
... L1: LINE=( ... ) L2: LINE=( ... ) MA1: MAXAMP,X_MAX=0.01,Y_MAX=0.005 MA2: MAXAMP,X_MAX=0.01,Y_MAX=0.002 BL1: LINE=(MA1,L1,MA2,L2) BL: LINE=(BL1,-BL1)
This is equivalent to
BL: LINE=(MA1,L1,MA2,L2,-L2,MA2,-L1,MA1)Note that the aperture MA1 is the aperture for all of the first instance of beamline L1, but that MA2 is the aperture for the second instance, -L1. This is probably not what was intended. To prevent this, it is recommended to always use MAXAMP elements in pairs:
BL1: LINE=(MA2,MA1,L1,MA1,MA2,L2) BL: LINE=(BL1,-BL1)which is equivalent to
BL: LINE=(MA2,MA1,L1,MA1,MA2,L2,-L2,MA2,MA1,-L1,MA1,MA2)Now, both instances of L1 have the aperture defined by MA1 and both instances of L2 have the aperture defined by MA2.